Method of galvanizing



July 28, 1931.

Patented July 28, 1931 PATENT OFFICE JULIAN L. SCHUELEB, F KOKOMO, INDIANA METHOD OF GALVANIZING Application led September 29, 1927. Serial No. 222,760.

My invention relates to the coating of metal and more particularly has reference to the galvanizing of wire and `sheets and similar materials.

I-Ieretofore, in coating metals, it has -been very diflicult to get relatively heavy coatings, especially so in galvanizing, which would adhere to the base metal, if the coated material was subjected to bending or severe forming. j

The principal object of this invention is to cause the adherence of. the galvanized coating to the metal base so that the coating will not flake or peel from said metal base, when the same is subjected to bending and forming operations.

Another object of the invention is to cause the galvanized coating to adhere more tightly to the metal base than is possible under ordinary galvanizing conditions.

A further obj ect of the invention is to allow heavier coatings to be carried on wire, sheets and similar materials, especially where such materials carry a galvanized coating.

Still another object of the invention is to prepare an iron or steel base which is to be galvanized, in such a manner, that the galvanized coating will readily adhere thereto in a manner superior to any ordinary and known process.

Further objects of the invention will more fully appear.

That the invention may be more 4easily understood, Fig. 1 is a diagrammatic view showing a typical layout for the practice of the method when galvanizing wire, and

Fig. 2 is a diagrammatic view of a layout for galvanizing sheets.

At the present time, so far as I am aware, there are no quick and cheap methods for coating wire, sheets and like materials with relatively heavy coatings of zinc where the coating will stand the action of forming and fabricating devices, without cracking or peeling.

It has been found, that bythe use of a very high grade zinc and allowing the material to pass very slowly through a molten zinc bath, fairly heavy coatings may be ob` tained which will stand forming. However,

it has been my experience that the use of such processes is very limited on account of the high cost of production; and such processes cannot be used for wire intended for farm fencing or barbed wire and the like, or for sheets to be used for forming Vinto cheap domesticarticles, on account of the cost and low production per galvanizing unit. On the other hand, if the wire or sheet is passed through the coating bath too quickly and a heavy coat allowed to remain on the same, a non-adherent coating is produced, especially if such materials be formed after coating.

The reason for such coatings cracking and peeling, is caused by the non-aiiinity of molten zinc for iron or steel, unless said. molten zinc is allowed to come in contact with the iron-or steel for a relatively long period 7 of time. It is' for this reason that low speeds through galvanizing baths are conducive to more adherent coatings on iron or steel passed therethrough. However, as -I previously stated, such a process is too costly for ordinary use.

I have discovered that if the iron or steel article (for the sake of brevity and clearness I will conne myself to iron or steel wire, hereinafter called wire) is subjected to a preliminary light coating or Hash coating of zinc, just prior to entering the molten zinc bath, then the molten zinc will adhere more firmly to the wire. The reason is this q molten zinc has more'aiiinity for zinc than it has for 85 iron or steel. Consequently by the use of a process whereby the zinc is firmly attached to, or bonded with, the steel base and then applying the molten zinc to the irmly attached z1nc, a coating is produced which will not 90 crack or peel from the iron orcsteel base. I accomplish such a preliminary coating by subjecting the wire to an electrolytic process just prior to subjecting it to the molten zinc bath. C 9 It is well known to those skilled inthe art that the applicatien of an electrolytic'zinc coating is a slow, tedious and fairly expensive process. Furthermore, such electrolytically applied coatings are porous, but are extremely adherent when properly applied. In the application of electrolytic Zinc, considerable time and low voltages, say 3-5 volts, are used.

Consequently, if this process were to be used, either very low speeds and resulting low production would ensue, or long coating tanks would have to be used, which is not economically practical.

I have discovered that all of these objections, except porosity of the coating, are obviated if I use higher voltages, such for eX- ample, as 90 volts, `and I can obtain an electrolytic coating in a very few seconds. Such a coating is very iirmly attached to and bonded with the metallic. base. By then passin this coated material into the molten Zinc secure an adherent coating, because the molten zinc amalgamates with the electrolytic zinc, which, in turn, is securely bonded with the metallic base, as before described. Furthermore, the porosity of the electrolytic Zinc coating is also an aid, because the molten zinc flows into these pores and helps form a mechanical or physical bond between the molten Zinc and electrolytic zinc.

I can also accentuate this bonding by giving the electrolytic coating a very slight acid etching before it passes into the molten zinc bath. This is also a physical or mechanical help in the bonding.

I am aware that coating by means of molten Zinc is not new, nor is the coating by electrolytically applied Zinc, new. However, so far as I am aware, the combination of the two steps is new, more especially my novel means for applying the electrolytic zinc. It is well known, that heavy, adherent zinc coatings on materials to be formed or fabricated are eX- tremely diicult to produce and my method produces such adherent coatings in a cheap, efficient and economical manner.

What I claim is l. The method of applying an adherent zinc coating to a metallic base, which consists in'lirst subjecting such metallic base to an electrolytic zinc coating bath; second, subjecting the same to an acid etching bath and lginelly subjecting the same to a molten zinc 2. The method of applying an adherent zinc coating to an iron or steel base, which consists in first subjecting such iron or steel base to an electrolytic zinc coating bath; second, subjecting the same to an acid etching bath and finally subjecting the same to a `molten Zinc bath.

3. The method of applying an adherent zinc coating to wire, which consists in first subjecting such wire to an electrolytic zinc coating bath; second, subjecting the same to an acid etching bath and finally subjecting the same to a molten zinc bath.

4. The method of applying an adherent zinc coating to sheets, which consists in first subjecting such sheets to an electrolytic zinc coating bath; second, subjecting the same to an acid etching bath and finally subjecting the same to a molten zinc bath.

5. The method of applying an adherent Zinc coat-ing to a metallic base, which consists in continuously moving such base and during such movement subjecting the same, lirst to an electrolytic zinc coating bath; second, subjecting the same to an acid etching bath and finally subjecting the same to a molten Zinc bath.

6. The method of applying an adherent Zinc coating to wire, which consists in continuously moving such wire and during such movement subjecting the same, first to an electrolytic zinc coating bath; second, sub-,Y

jecting the same to an acid etching bath and nally subjecting the same to a molten zinc ath.

7. The method of applying an adherent zinc coating to sheets, which consists in continuously moving such sheets and during such movement subjecting the same, first to an electrolytic Zinc coating bath; second, subjecting the same to an acid etching bath and naly subjecting the same to a molten zinc 8. The method of applying an adherent zinc coating to articles, which consists in applying a thin initial coating of electrolytic zinc to said articles, lightly etching the initial coating, and finally subjecting the initially coated and etched article to a molten zinc bath.

9. The method of applying an adherent zinc coating to articles, which consists in applying a thin coating of electrolytiozinc to said articles, subjecting the article to an acid etching bath to roughen the surface of the initial coat and finally subjecting the initially coated and etched article to a ymolten zinc bath.

In witness whereof I have lhereunto set my hand this 26th day of September, 1927.

JULIAN L. SCHUELER. 

